Ch. 14 - Brain and Cranial Nerves I

Question 1

What are the 4 main parts of the brain?

Answer 1

brainstem, diencephalon, cerebrum, cerebellum

Question 2

How does the dura mater differ between the brain and the spinal cord?

Answer 2

brain - 2 layers of dura mater (periosteal and meningeal layers) that fuse together except where they separate to enclose venous sinuses

Question 3

What are the 3 extensions of the dura mater and what do they do?

Answer 3

falx cerebri, falx cerebelli, tentorium cerebelli; separates parts of the brain

Question 4

What does the falx cerebri separate?

Answer 4

cerebral hemispheres

Question 5

What does the falx cerebelli separate?

Answer 5

cerebellar hemispheres

Question 6

What does the tentorium cerebelli separate?

Answer 6

cerebrum from cerebellum

Question 7

What are the 3 components of the blood brain barrier?

Answer 7

1. tight junctions
2. basement membrane
3. astrocytes

Question 8

What are function of CSF?

Answer 8

1. shock absorption to protect CNS tissues
2. maintain optimal chem env to maintain resting MP of neurons
3. medium for exchange of nutrients/waste bt blood and nervous tissue

Question 9

Where are the lateral ventricles found?

Answer 9

in each hemisphere of cerebrum; separated by septum pellucidum

Question 10

Where is the third ventricle found?

Answer 10

along midline sup to hypothalamus; bt R and L halves of thalamus

Question 11

Where is the fourth ventricle found/

Answer 11

bt brain stem and cerebellum

Question 12

How is CSF formed?

Answer 12

• secreted by ependymal cells in walls of choroid plexuses

Question 13

How is CSF reabsorbed?

Answer 13

via arachnoid villi (grapelike clusters of arachnoid mater that penetrate dural venous sinus)

Question 14

What are the 3 structures of the brainstem?

Answer 14

medulla oblongata, pons, midbrain

Question 15

What does the medulla oblongata contain?

Answer 15

extension of spinal cord containing ascending sensory tracts, descending motor tracts, nuclei

Question 16

What is the function of pyramids in the medulla oblongata?

Answer 16

control voluntary movements of limbs and trunks; decussation (crossing)

Question 17

What is the function of olives in the medulla oblongata?

Answer 17

located laterally to each pyramid; receives input from cerebral cortex/midbrain/spinal cord and sends output to cerebellum
- gives precision to movements

Question 18

What are the main centers (nuclei) in the medulla?

Answer 18

CV, respiratory, reflex

Question 19

Where is the pons located and what is its function?

Answer 19

superior to medula; connects R and L sides of cerebellum; relays nerve impulses related to voluntary sk movements from cerebral cortex to cerebellum

Question 20

Where is the midbrain located and what is its function?

Answer 20

contains cerebral aqueduct that contains third and fourth ventricles

contains sensory/motor tracts, nuclei

Question 21

What are cerebral peduncles in the anterior midbrain and what is their function?

Answer 21

paired bundles of axons; ascending axons carry sensory info to thalamus; descending nerve tracts run to and from cerebrum, pons, medulla, SC

Question 22

What are some distinct features of the posterior midbrain?

Answer 22

has 4 elevations:

2 superior elevations (superior colliculi) & 2 inferior elevations (inferior colliculi)

Question 23

What is the function of superior colliculi?

Answer 23

reflex centers for visual activities (pupillary/accommodation reflexes)

Question 24

What is the function of inferior colliculi?

Answer 24

part of auditory pathway

reflex center for startle reflex

Question 25

What are other nuclei found in the midbrain?

Answer 25

substantia nigra, red nuclei, nuclei for CN III & IV

Question 26

What is the function of the substantia nigra?

Answer 26

neurons release dopamine; help control subconscious muscle activity

Question 27

What is the reticular formation and what does it contain?

Answer 27

broad region throughout brainstem where white and matter form a netlike arrangement; contains reticular activating system (RAS)

Question 28

What are some functions of the RAS?

Answer 28

1. alerts cerebral cortex to sensory signals 2. maintain consciousness, alertness 3. filters stimuli (visual and auditory) to prevent sensory overload